Dispersible moist wipes are generally intended to be used and then flushed down a toilet. Accordingly, it is desirable for such flushable moist wipes to have an in-use strength sufficient to withstand a user's extraction of the wipe from a dispenser and the user's wiping activity, but then relatively quickly breakdown and disperse in household and municipal sanitization systems, such as sewer or septic systems. Some municipalities may define “flushable” through various regulations. Flushable moist wipes must meet these regulations to allow for compatibility with home plumbing fixtures and drain lines, as well as the disposal of the product in onsite and municipal wastewater treatment systems.
One challenge for some known flushable moist wipes is that it takes a relatively longer time for them to break down in a sanitation system as compared to conventional, dry toilet tissue thereby creating a risk of blockage in toilets, drainage pipes, and water conveyance and treatment systems. Dry toilet tissue typically exhibits lower post-use strength upon exposure to tap water, whereas some known flushable moist wipes require a relatively long period of time and/or significant agitation within tap water for their post-use strength to decrease sufficiently to allow them to disperse. Attempts to address this issue, such as making the wipes to disperse more quickly, may reduce the in-use strength of the flushable moist wipes below a minimum level deemed acceptable by users.
Some known flushable moist wipes are formed by entangling fibers in a nonwoven web. A nonwoven web is a structure of individual fibers which are interlaid to form a matrix, but not in an identifiable repeating manner. While the entangled fibers themselves may disperse relatively quickly, known wipes often require additional structure to improve in-use strength. For example, some known wipes use a net having fibers entangled therewith. The net provides additional cohesion to the entangled fibers for an increased in-use strength. However, such nets do not disperse upon flushing.
Some known moist wipes obtain increased in-use strength by entangling bi-component fibers in the nonwoven web. After entanglement, the bi-component fibers are thermoplastically bonded together to increase in-use strength. However, the thermoplastically bonded fibers negatively impact the ability of the moist wipe to disperse in a sanitization system in a timely fashion. That is, the bi-component fibers and thus the moist wipe containing the bi-component fibers often do not readily disperse when flushed down a toilet.
Other known flushable moist wipes add a triggerable salt-sensitive binder. The binder attaches to the cellulose fibers of the wipes in a formulation containing a salt solution, yielding a relatively high in-use strength. When the used moist wipes are exposed to the water of the toilet and/or sewer system, the binder swells thereby allowing and potentially even assisting in the wipes falling apart, which allows for relatively rapid dispersal of the wipes. However, such binders are relatively costly.
Still other known flushable moist wipes incorporate a relatively high quantity of synthetic fibers to increase the in-use strength. However, the ability of such wipes to disperse in a timely fashion is correspondingly reduced. In addition, a higher cost of synthetic fibers relative to natural fibers causes a corresponding increase in cost of such known moist wipes.
Thus, there is a need to provide a wet wipe made from a dispersible nonwoven tissue web that provides an in-use strength expected by consumers, disperses sufficiently quickly to be flushable without creating potential problems for household and municipal sanitation systems, and is cost-effective to produce.